The research proposal focuses on the characterization of an inherited murine neurodegenerative disorder that appears to represent an excellent genetic model of a group of human diseases termed the neuronal ceroid lipofuscinoses (NCL). Because the murine disorder was initially believed to be a motor neuron disease, it has been designated motor neuron degeneration (mnd). However, studies from two laboratories, including our own, indicate that the disease clearly resembles NCL. In this proposal, histological, immunocytochemical, and molecular biological techniques will be used to study the process of neuronal degeneration in mnd mice, and a major goal of these studies is to identify the mnd gene. To accomplish this goal, mnd/mnd mice will be crossed to the distantly related species Mus castaneous and backcrossed to mnd/mnd mice. A set of molecular probes developed at the Massachusetts Institute of Technology and the Whitehead Institute, specific for the region of mouse chromosome 8 where mnd resides, will be used for rapid, accurate mapping of the mnd locus. Chromosome walking (positional cloning) using cosmids and yeast artificial chromosomes will be performed to isolate the region of DNA that contains the gene responsible for the mnd phenotype. Once this region has been isolated, exon amplification techniques will be used to identify the exact site at which the gene resides. The gene will then be sequenced to determine the nature of the encoded protein. Finally, tissues from patients with Batten's disease, the most common human form of NCL, will be screened for possible mutations. If the gene responsible for the mnd phenotype is the same one affected in Batten's disease, then a genetic test may be developed for affected patients and carriers. The multidisciplinary training afforded through this proposal will provide a foundation for the integration of modern molecular neurobiology with clinical activities centered around the diagnosis and treatment of patients with neurodegenerative disorders, particularly those involving neuromuscular systems.